cGMP-independent anti-apoptotic effect of nitric oxide on thapsigargin-induced apoptosis in the pancreatic beta-cell line INS-1.
OBJECTIVE
Low concentrations of nitric oxide (NO) produced by constitutive NO synthase (cNOS) in pancreatic beta-cells have been suggested to be a physiological regulator of insulin secretion. In contrast, excessive NO produced by inducible NO synthase is known to mediate beta-cell apoptosis. The aim of the present study was to investigate the effect of low concentrations of NO on beta-cell apoptosis.


METHODS
Apoptosis of the pancreatic beta-cell line INS-1 was quantitatively determined by Annexin V flow cytometry.


RESULTS
The 24-h incubation with 1 mM DETA/NO, a long half-life NO donor, induced beta-cell apoptosis, which was insensitive to the soluble guanylate cyclase (sGC) inhibitor ODQ. In contrast, DETA/NO at lower concentrations until 300 microM concentration-dependently decreased the apoptosis induced by thapsigargin, an inhibitor of endoplasmic reticulum Ca2+-ATPase. ODQ did not affect the anti-apoptotic effect of DETA/NO. Moreover, neither the cGMP analogue 8-Br-cGMP nor the sGC activator YC-1 mimicked the anti-apoptotic effect of DETA/NO.


CONCLUSIONS
These results suggest that low levels of NO protect beta-cells from thapsigargin-induced apoptosis in a cGMP-independent manner.
Noguchi
Akiko
A
Department of Pharmacology, Graduate School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka 422-8526, Japan.
Takada
Masahiro
M
Nakayama
Koichi
K
Ishikawa
Tomohisa
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D018929:Cell Culture Techniques; D002460:Cell Line; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D019284:Thapsigargin / Q000494:pharmacology; D014226:Triazenes / Q000494:pharmacology
C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D011810:Quinoxalines; D014226:Triazenes; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D019284:Thapsigargin; D006152:Cyclic GMP